A gay man who mistakenly went to a Chelsea club on a “straight night” was tossed out and brutally attacked by two men – one of them a security guard, police said.

The apparent bias incident began at 10:20 p.m. Saturday, when the victim walked into Club Pure at 101 Seventh Ave., where he had gone on several prior occasions to attend gay soirées, police said.

But on Saturday night, the 29-year-old man was confronted by another man who grabbed him and tossed him outside.

Igor Llioukhov, a 37-year-old security guard at the club, then punched the man in the face and spewed anti-gay insults at him, cops said. Police were called and arrested Llioukhov on charges of assault and aggravated harassment. The club’s manager was also issued summonses for having unlicensed security guards and a disorderly premises.